The invention relates to a method for controlling a hydrocarbon vapor reforming reaction using a combustion chamber containing burners and tubes, said tubes being filled with catalysts and capable of being crossed by a mixture of hydrocarbons and vapor, the burners being arranged so as to transfer their combustion heat to the mixture of hydrocarbons and vapor through the walls of the tubes, wherein the temperature T of the wall of each tube is measured in the downstream part of the tube, and if for at least one tube, the measured temperature“is higher or equal to the MOT (DTT-15° C.), DTT being the design temperature of the measured tube, the functional parameters of the reforming method are then modified so as to decrease the measured temperature T of this tube down to a value lower than the MOT.